Vertically centered block (absolute)

HTML

<div id="container">
    <div id="content">Vertically centered block</div>
</div>

CSS

#container {
    position: relative;
    display: block;
    height: 200px;
    background: #FFCCFF;
}


#content {
    display: block;
    position: absolute;
    margin: auto;
    top: 0;
    bottom: 0;
    text-align: center;
    width: 100%;
    height: 100px;
    background: #CCFFCC;
}